This invention generally relates to control systems and, more specifically, to shut-off control systems for oil and gas wells upon detection of an abnormal condition.
Oil and gas wells are particularly vulnerable to terrorist activities. Such wells are normally in developed oil producing regions or in oil and/or gas exploration cites, most frequently removed from populated areas. Such wells are popular targets of terrorists because of the ease of performing terrorist acts in such secluded areas and also because such acts can create substantial damage. Aside from damage to the well(s) and the potential losses in revenues as a result of oil and/or gas being released to the surrounding areas, the potential for personal injuries and for damage to the environment is also significant. See, for example, a description of the devastation which took place in Kuwait when over seven hundred wells were set aflame "the Persian Gulf after the Storm", National Geographic, Vol. 180, No. 2 August 1991, pps. 2-35. Enormous clouds of smoke threatened crops in the region with acid rain at least as far as east as India and Pakistan. Black rain and black snow had also been reported in Bulgaria, Turkey and Southern Soviet Union, Afghanistan and Northern India, with such disastrous consequences being easily achievable by directed terrorists, oil and gas wells continue to be exposed to damage as occurred in Kuwait during the Persian Gulf War. Unfortunately, skilled and well-funded terrorists normally have the ability to by-pass fail-safe systems and penetrate security zones to cause damage of the type which took place in Kuwait. Simple measures, therefore, such as providing perimeter fencing, security in the form of alarms, etc., can do little to stop terrorist or natural disasters such as earthquakes, tornadoes, etc. Smoke from oil wells set on fire by Iraqi troops caused health and environmental problems across Kuwait and disrupted weather patterns up to fifteen hundred miles away. Polluted fallout from the smoke had coated as much as seventy-five percent of Kuwait's desert with a tar-like layer that disrupted fragile plant and animal life. The fallout from the smoke also contaminated the Persian Gulf, threatening the desalinization plants along the Gulf Coast that provided fresh water to Kuwait and Saudi Arabia. Such soot was particularly troublesome because, when combined with the chlorine used to purify water at the plants, formed chlorinated hydrocarbon compounds, which are believed to be carcinogenic.
Kuwait officials estimated that approximately six million barrels of oil a day were going up in smoke at a cost of more than $1,000 a second. Firefighting efforts, at their peak, involved ten thousand workers from thirty-four countries. Efforts to stop the burning wells cost between 1.5 and 2 billion dollars according to Kuwait and Western estimates. Approximately six hundred million barrels of oil worth a total of twelve billion dollars had been lost in the fires, with an 25-50 million barrels of oil having been spilled on Kuwait's desert floor.